JP2013219842A - Power system load frequency control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load frequency control system which can improve a demand-supply operation for a power system and control performance, be effective for improving economical efficiency, and reduce the load on an operator.SOLUTION: A power system load frequency control system comprises: an AR calculation unit 24 which calculates area request power (AR) by using a frequency change amount (ΔF) and a linkage line trend change amount (ΔPT); an AR resolving unit 25 which resolves the frequency of the calculated AR; an AR distribution unit 26 which distributes the frequency-resolved AR into respective generators; a target command value calculation unit 22 which calculates a target command value based on the distributed AR and an ELD schedule calculated by an economical load distribution control (ELD); and a command value transmission unit 23 which transfers the target command value to the generator. An LFC target/exclusion switching unit 6 which switches, according to magnitude of the AR, the generator targeted for the load frequency control to the generator not targeted for the load frequency control, or the generator not targeted for the load frequency control to the generator targeted for the load frequency control, is arranged at the output side of the AR calculation unit 24.

Description

  Embodiments described herein relate generally to a power system load frequency control system capable of improving the supply and demand control performance of a power system.

  In general, the reliability of the power system includes voltage, frequency, and uninterruptible supply. Among them, frequency stabilization is performed by load frequency control (LFC). This load frequency control is a control method for maintaining the frequency of the entire system at a specified value by adjusting the output of the generator.

In LFC, it can mainly be classified into the following three systems.
The first method detects a frequency change amount (ΔF), adjusts the output of the generator so as to reduce it, and keeps only the system frequency at a specified value (FFC: Flat Frequency Control Method). Control).

  The second method detects constant interconnection power flow variation (ΔPT), adjusts the output of the generator so as to reduce it, and keeps only the interconnection power flow at a specified value. This is a control method (FTC: Flat Tie Line Control).

  The third method detects the amount of change in frequency (ΔF) and the amount of change in interconnected power flow (ΔPT), calculates the regional demand power (AR) that is an unbalanced supply-demand balance from these, and according to the amount This is a frequency bias link line power control system (TBC) that adjusts the output of the generator.

  Of the above three methods, the TBC method is currently used in most Japanese electric power companies. This TBC method is performed in the following procedure.

  First, using the frequency change amount (ΔF) and the interconnected line power flow change amount (ΔPT), the regional required power (AR) is calculated by the equation (1).

  If the value of the regional required power (AR) is positive, it is necessary to increase the generator output as a whole system. Conversely, if the value is negative, it is necessary to decrease the generator output as a whole system.

  In order to filter the regional required power (AR), filtering is performed by exponential smoothing using the past regional required power (AR), and the regional required power (AR) is reduced to a low speed machine (for example, a thermal power machine having a slow output change rate). ) And a high-speed machine (for example, a hydraulic machine with a fast output change speed). In addition, there is a method in which the regional required power (AR) is frequency-resolved, and those having a short period component are shared by a low speed machine, and those having a long period component are shared by a high speed machine.

  When distributing the filtered or frequency-resolved regional demand power (AR) to each generator, the output change of the generator for all the generators for which load frequency control is performed for each low-speed machine and high-speed machine Allocate by speed ratio or output margin ratio.

  Moreover, when calculating the target command value of each generator, it calculates by adding the allocated regional demand power (AR) and the ELD schedule calculated by the economic load distribution control (ELD).

  Each generator receives the target command value from the central power supply command station, and the output of each generator fluctuates. As a result, the system frequency and the interconnection current flow change.

Japanese Patent No. 3930218

"Power System Engineering" Maruzen P163

  The LFC controls the frequency of the entire system and the interconnection power flow between power companies close to the specified values by adjusting the output of the generator according to the method described above, but the following (1) to ( The problem like 3) is mentioned.

(1) The regional required power (AR) filtered or frequency-resolved in the above procedure will be distributed to each generator. If the number of LFC target generators is small, the remaining capacity of these generators (current output) If the difference between the output and the maximum output or the difference between the current output and the minimum output) is small, the regional required power (AR) cannot be sufficiently distributed, and there is a possibility that residual distribution may occur, which may hinder control performance. .

(2) When the number of LFC target generators is small as described above, the operator increases the number of LFC target generators by manual switching according to the situation (that is, switches from the LFC excluded generator to the LFC target generator), etc. Measures are taken.

  However, if the regional demand power (AR) suddenly increases and a large amount of adjustment (distribution amount for each generator) is required, the maximum output, the minimum output, or the base output such as the ELD schedule, Even a generator that does not want to change its output may be forced to switch to an LFC target generator. For this reason, the operator is burdened with switching between “target” and “exclusion” of the LFC generator. In addition, if the timing of switching to the LFC target generator is delayed, the regional required power (AR) cannot be sufficiently distributed, resulting in an increase in the remaining control, and the control performance may be reduced.

(3) On the other hand, the regional power requirement (AR) does not always fluctuate greatly (for example, 100 MW or more) but may fluctuate (for example, 10 MW or less) depending on the situation. In the case of generators subject to LFC, the regional required power (AR) will be allocated to generators that do not want to fluctuate as much as possible from the maximum output, minimum output, or base output such as ELD schedule. There is a risk of deteriorating the economy by deviating from the value or deviating from the base output.

  An embodiment of the present invention has been made in view of the above circumstances, and is a load frequency control system that can improve the supply and demand operation and control performance of an electric power system, is effective in improving economy, and reduces the load on the operator. The purpose is to provide.

  In order to achieve the above-described object, an embodiment of the present invention includes a ΔF detection unit that detects a frequency change amount (ΔF) in a power system, a ΔPT detection unit that detects a connection power flow change amount (ΔPT), An AR calculation unit that calculates the regional required power (AR) using the frequency change amount (ΔF) and the interconnection power flow change amount (ΔPT), and an AR decomposition unit that frequency-decomposes the calculated local request power (AR) A target command value from an AR distribution unit that distributes frequency-resolved regional required power (AR) for each generator, and an ELD schedule calculated by the allocated regional required power (AR) and economic load distribution control (ELD) In a power system load frequency control system having a target command value calculation unit that calculates the target command value and a command value transmission unit that transmits the target command value to the generator, the regional required power (AR) is provided on the output side of the AR distribution unit. Depending on the size of the switches the generator load frequency control object outside load frequency control subject, or characterized in that a switching unit for switching the load frequency control exempt from the generator to the load frequency control object.

The block diagram which shows the structure of the electric power system load frequency control system of each embodiment of this invention. The flowchart which shows the distribution procedure of the area | region request | requirement electric power (AR) to the generator using the electric power grid load frequency control system of FIG. The flowchart which shows the procedure which determines distribution of the area | region required electric power (AR) by the LFC object / exclusion switching part of FIG. The flowchart which shows the switching procedure from the LFC exclusion generator in 1st Embodiment to the LFC object generator. The image figure which shows the switching timing from the LFC exclusion generator in 1st Embodiment to the LFC object generator (in the case of the generator which can raise an output). The image figure which shows the switching timing from the LFC exclusion generator in 1st Embodiment to the LFC object generator (in the case of the generator which can reduce output). The flowchart which shows the switching procedure from the LFC object generator in 2nd Embodiment to the LFC exclusion generator. The image figure which shows the switching timing from the LFC object generator in 2nd Embodiment to the LFC exclusion generator. The image figure which shows the switching timing from the LFC exclusion generator before the averaging process in 3rd Embodiment to the LFC object generator (in the case of the generator which can raise an output). The image figure which shows the switching timing from the LFC exclusion generator after the averaging process in 3rd Embodiment to the LFC object generator (in the case of the generator which can raise an output). The image figure which shows the switching timing from the LFC exclusion generator before the averaging process in 3rd Embodiment to the LFC object generator (in the case of the generator which can reduce output). The image figure which shows the switching timing from the LFC exclusion generator after the averaging process in 3rd Embodiment to the LFC object generator (in the case of the generator which can reduce output). The flowchart which shows the change procedure to the smoothing process of AR in 3rd Embodiment. The flowchart which shows the change procedure to the priority order mode in 4th Embodiment.

Embodiments of the present invention will be specifically described below with reference to the drawings.
(System configuration)
FIG. 1 is a block diagram showing a configuration of a power system load frequency control system according to each embodiment of the present invention.

  In FIG. 1, a power system 1 has a plurality of generators G 1, G 2,..., Gn inside thereof, and is connected to another system 3 via a connection line 4.

  Each generator G1, G2,..., Gn is connected to a respective generator output signal input unit 20-1, 20-2,..., 20-n in the computer 2 via a detection signal line 11. It is connected to each command value transmission unit 23-1, 23-2,..., 23-n via a control signal line 12. Further, the generator output signal input units 20-1, 20-2,..., 20-n and the command value transmission units 23-1, 23-2,. , 22-2,..., 22-n.

In addition, a data detection unit 10 having a ΔPT detection unit and a ΔF detection unit is provided inside the electric power system 1, and is connected to an AR calculation unit 24 provided inside the computer 2 through a signal line 13. ing.
Further, on the output side of the AR calculation unit 24, an LFC target / exclusion switching unit 6, an AR decomposition unit 25, and an AR distribution unit 26 are sequentially arranged. The AR decomposition unit 25 is also connected to an ELD schedule calculation unit 30, and this ELD schedule calculation unit 30 is further connected to target command value creation units 22-1 to 22-n. In addition, a power generation end total demand calculation unit 27 is disposed on the output side of the generator output signal input units 20-1, 20-2,..., 20-n, and online on the output side of the power generation end total demand calculation unit 27. A forecast demand unit 28 is provided. Both the online forecast demand unit 28 and the previous day operation plan unit 29 are connected to the ELD schedule calculation unit 30.

  The generator output signal input units 20-1, 20-2,..., 20-n output the generator output signals to the target command value creating units 22-1, 22-2,. . Target command value creation units 22-1, 22-2,..., 22-n create each generator output signal based on the received signal, and command value transmission units 23-1, 23-2,. 23-n.

  The AR calculation unit 24 inputs the frequency change amount (ΔF) and the interconnection power flow change amount (ΔPT) detected from the data detection unit 10 of the power system, and calculates the AR value. The output from the AR calculation unit 24 is input to the AR decomposition unit 25, and the target command value generation units 22-1, 22-2,. 22-n.

  In addition, the LFC target / exclusion switching unit 6 has a function of switching the generator that performs AR distribution in the AR distribution unit 26.

  The power generation end total demand calculation unit 27 takes in the generator outputs from the respective generator output signal input units 20-1, 20-2,..., 20-n, and calculates the power generation end total demand. The online forecast demand by the online forecast demand unit 28 and the previous day operation plan by the previous day operation plan unit 29 are arranged to be input to the ELD schedule calculation unit 30. The calculation result (ELD value) of the economic load distribution by the ELD schedule calculation unit 30 is input to each target command value creation unit 22-1, 22-2, ..., 22-n.

  As described above, the inputs to the target command value creation units 22-1, 22-2,..., 22-n are input to the generator output input units 20-1, 20-2,. There are an output, a distribution amount from the AR distribution unit 26, and an economic load distribution calculation result (ELD value) from the ELD schedule calculation unit 30. Each of the target command value creation units 22-1, 22-2,..., 22-n inputs the output signal, the AR value, and the ELD value of each generator G1, G2,. create.

  The computer 2 is provided with an MMI (Man Machine Interface) 5 for exchanging information between the worker and the machine.

(Processing procedure in the system)
FIG. 2 is a flowchart showing a procedure for allocating regional required power (AR) to generators using the power system load frequency control system of FIG.

  First, in step S20, the amount of change in frequency (ΔF) and the amount of change in interconnected power flow (ΔPT) detected from the power system are input to the AR calculator 24 in the computer 2, where the regional required power (AR) is calculated. Calculated.

  Next, in step S <b> 21, the AR required power (AR) is frequency-resolved by the AR decomposition unit 25. In step S22, the AR distribution unit 26 calculates the distribution amount of the regional required power (AR) for each generator. In step S23, the target command value creation units 22-1, 22-2, ..., 22-n. Respectively.

  Thereafter, in step S24, the target command values from the target command value creation units 22-1, 22-2,..., 22-n are transmitted to the command value transmission means 23-1, 23-2,. In step S25, a command is issued to each of the generators G1, G2,.

  On the other hand, in step S201, the online predicted demand operation data is created by the online predicted demand unit 28, and the previous day operation plan operation data is created by the previous day operation plan unit 29.

  Further, in step S202, the calculation result (ELD value) of the economic load distribution is created by the ELD schedule calculation unit 30 and input to each target command value creation unit 22-1, 22-2, ..., 22-n.

  In step S205, the LFC target / exclusion switching unit 6 switches the generator that performs AR distribution.

  FIG. 3 is a flowchart showing a procedure for determining the distribution of the regional required power (AR) by the LFC target / exclusion switching unit 6.

  First, in step S31, the LFC target / exclusion switching unit 6 determines whether or not the generator is an LFC target based on a setting predetermined for each generator or an arbitrary setting by the operator. If the generator is an LFC target (Yes in step S31), the regional required power (AR) is allocated in step S32. On the other hand, in the case of a generator that is not subject to LFC (No in step S31), the regional required power (AR) is not distributed in step S33.

  The system configuration common to each embodiment of the present invention and the relationship between the processes have been described above. The processing procedure in each embodiment will be described below.

[First Embodiment]
(Procedure for switching from an LFC-excluded generator to an LFC target generator)
Hereinafter, the switching procedure from the LFC excluded generator to the LFC target generator in the first embodiment will be described with reference to FIGS. 4 to 6.

  FIG. 4 is a flowchart showing a switching procedure from the LFC excluded generator to the LFC target generator. As shown in FIG. 4, in step S41, the LFC target / exclusion switching unit 6 determines whether or not the regional required power (AR) from the AR calculation unit 24 exceeds a specific threshold A in the positive direction. If exceeded (Yes in step S41), the generator operating at the minimum output, or the generator that is optionally set to increase the output in the plus method, is switched from the LFC excluded generator to the LFC target generator, In these generators, the regional required power (AR) can be allocated (step S42).

  In other words, the processing procedure is based on the idea that when the regional required power (AR) is excessively shifted in the positive direction, the number of LFC target generators is increased and the residual distribution of the regional required power (AR) is eliminated. .

  Here, the period of becoming an LFC target generator is only a period in which AR exceeds the threshold A and enters the region I shown in FIG. 5, and when it falls below the threshold A, the generator is switched again to the LFC excluded generator. In the LFC-excluded generator, a generator that can be switched to an LFC target generator can be selected in advance, and an operator can arbitrarily change the generator selection.

  On the other hand, if the regional required power (AR) does not exceed the specific threshold value A in the positive direction at step S41 in FIG. 4 (No at step S41), the regional required power (AR) is negative at step S43. It is determined whether the direction is smaller than a specific threshold B. If the generator is small (Yes in step S43), the generator operating at the maximum output, or the generator that is optionally set to be able to increase the output by the minus method, is switched from the LFC excluded generator to the LFC target generator. Even in this generator, the regional required power (AR) can be allocated (step S44). On the other hand, if the regional required power (AR) is greater than or equal to the specific threshold value B in the negative direction (No in step S43), the process ends without performing the process.

  That is, the processing procedure is based on the idea of increasing the number of LFC target generators and eliminating the remaining allocation of regional required power (AR) when the regional required power (AR) is excessively shifted in the negative direction. .

  Here, the period during which the generator is an LFC target generator is only a period in which AR exceeds the threshold value B in the minus direction and enters the region II shown in FIG. 6, and if it exceeds the threshold value, it is switched again to the LFC excluded generator. In the LFC-excluded generator, a generator that can be switched to an LFC target generator can be selected in advance, and an operator can arbitrarily change the generator selection.

(effect)
According to the present embodiment, when the regional required power (AR) is excessively shifted in the positive direction or the negative direction, by increasing the number of LFC target generators, the remaining distribution can be reduced and the control performance can be improved. It becomes. In addition, the LFC target / exclusion can be automatically switched, which reduces the burden on the operator.

[Second Embodiment]
(Procedure for switching from an LFC target generator to an LFC excluded generator)
Hereinafter, the switching procedure from the LFC target generator to the LFC excluded generator in the second embodiment will be described with reference to FIGS. 7 and 8.

  FIG. 7 is a flowchart showing a switching procedure from the LFC target generator to the LFC excluded generator. As shown in FIG. 7, in step S51, the LFC target / exclusion switching unit 6 determines whether or not the regional required power (AR) from the AR calculation unit 24 is less than a specific threshold value C (first threshold value) in the positive direction. Determine. If it is less (Yes in Step S51), it is determined in Step S52 whether or not the regional required power (AR) has exceeded a specific threshold value D (second threshold value) in the negative direction. When the specific threshold value D is exceeded (Yes in step S52), LFC is excluded from the LFC target generators for generators operating at the minimum output or generators that can optionally be increased in output by the positive method. Switch to the generator (step S53).

  On the other hand, if the regional required power (AR) is greater than or equal to the specific threshold value C in the positive direction (No in Step S51) in Step S51, and the regional required power (AR) is less than or equal to the specific threshold value D in the negative direction in Step S52. In the case (No in step S51), the process ends without performing the process.

  In other words, if the regional required power (AR) is less than threshold C and exceeds threshold D, the generator operating at the minimum output, or the generator that is optionally set to be able to increase the output by the plus method, is subject to LFC Switching from generators to LFC-excluded generators, and regional generator power (AR) will not be allocated to those generators.

  In other words, when the regional required power (AR) is small, it is based on the idea that the regional required power (AR) is not distributed to the generators near the maximum and minimum outputs and the base output.

  Here, as shown in FIG. 8, the period to become an LFC-excluded generator is only a period formed between the threshold value C and the threshold value D and AR is included in the region III. It is switched to a generator. In the LFC target generator, a generator that can be switched to an LFC-excluded generator can be selected in advance, and an operator can arbitrarily change the generator selection.

(effect)
According to the present embodiment, it is possible to automatically switch an LFC target generator to an LFC excluded generator for a generator near the base output such as an ELD schedule. As a result, operation close to the maximum economy is possible without allocating regional required power (AR), which is effective for improving economic efficiency.

[Third Embodiment]
(Procedure to suppress LFC switching by AR smoothing)
Hereinafter, the LFC switching suppression procedure in the third embodiment will be described with reference to FIGS. 9 to 13.

  In the first embodiment, when the regional required power (AR) exceeds a predetermined threshold, the LFC-excluded generator is automatically switched to the LFC target generator. However, depending on the waveform of the AR value, FIG. As shown, there is a possibility that the threshold A ′ is frequently exceeded and the region IV is entered, and LFC target / exclusion switching is performed.

  In order to avoid this, in the present embodiment, the LFC target / exclusion switching unit 6 performs a smoothing process, such as a moving average (for example, cutting a periodic component of 10 seconds or less) on the regional required power (AR). And convert to a relaxed AR value as shown in FIG. The LFC target / exclusion switching unit 6 similarly performs threshold determination for the regional required power (AR) after the moving average, and only the period from the LFC exclusion to the target exceeds the threshold A ′ and enters the region IV. Switch over.

FIG. 10 shows an example of a generator capable of increasing the output, but a generator capable of decreasing the output can be considered in the same manner.
That is, depending on the waveform of the AR value, as shown in FIG. 11, there is a possibility that the threshold value B ′ is frequently exceeded and the region V is entered, and the LFC target / exclusion is switched. For this reason, a smoothing process such as a moving average (for example, a period component of 10 seconds or less is cut) is performed, and converted to a relaxed AR value as shown in FIG. For this AR value, the LFC target / exclusion switching unit 6 similarly performs threshold determination, and switches from LFC exclusion to target only during the period when the threshold value B ′ is exceeded and enters the region V.

  FIG. 13 is a flowchart illustrating a change procedure to the AR smoothing process according to the third embodiment. As shown in FIG. 13, in step S61, the LFC target / exclusion switching unit 6 counts how many times the LFC excluded generator is switched to the LFC target generator within a specified time (for example, 5 minutes). Then, it is determined whether or not it is a predetermined specified number of times (for example, 10 times) or less. If the number is less than the specified number (Yes in step S61), the process is performed in the normal mode (FIGS. 9 and 11) according to the first embodiment (step S62).

  On the other hand, when the specified number of times is exceeded (No in step S61), the process is performed in the moving average mode (FIGS. 10 and 12) of the present embodiment (step S63).

  This process can be performed separately for each of the generator capable of increasing the output and the generator capable of decreasing the output.

(effect)
According to the present embodiment, it is possible to suppress frequent switching of LFC objects / exclusions, and it is possible to reduce the burden on the generator (suppress the deterioration of the generator).

[Fourth Embodiment]
(Procedure for changing to priority mode)
The procedure for changing to the priority mode in the fourth embodiment will be described below with reference to FIG.

  In the first or second embodiment, the LFC target / exclusion is switched according to the regional required power (AR), but the number of generators to be switched is not limited to one, It is also possible to become. In that case, it is possible to simultaneously switch all of the generators, but in this embodiment, so that the operator can arbitrarily set the priority and select the generator, The procedure has a selection mode so that it is possible to arbitrarily determine whether or not to switch the generator.

  FIG. 14 is a flowchart showing a procedure for changing to the priority mode in the fourth embodiment. As shown in FIG. 14, in this embodiment, first, in step S71, it is determined whether or not there is only one LFC target / excluded generator. In the case of one unit, processing is performed in the normal switching mode described in the first or second embodiment (step S72). On the other hand, in the case of a plurality of units (No in step S71), the operator can arbitrarily set a priority and select a generator, or can arbitrarily determine whether or not to switch the generator. Processing is performed according to the mode (step S73).

(effect)
According to the present embodiment, it is possible to arbitrarily select a generator to be a target / excluded LFC. Therefore, operation according to the driving situation is possible.

[Other embodiments]
(1) In the first embodiment, the LFC target / exclusion switching unit 6 determines whether or not the regional required power (AR) has exceeded a specific threshold value A in the positive direction (step S41), and then in the negative direction. Although it is determined whether or not it is smaller than the specific threshold value B (step S43), it can be reversed. That is, it may be determined whether or not the specific threshold value A in the positive direction is exceeded after determining whether or not the specific value B is smaller than the specific threshold value B in the negative direction.

(2) In the second embodiment, the LFC target / exclusion switching unit 6 determines whether or not the regional required power (AR) is less than a specific threshold value C in the positive direction (step S51), and then specifies the negative direction. It has been determined whether or not the threshold value D has been exceeded (step S52), but this can be reversed. In other words, after determining whether or not the specific threshold value D in the negative direction has been exceeded, it is also possible to determine whether or not it is less than the specific threshold value C in the positive direction.

(3) Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Electric power system 2 ... Computer 3 ... Other system 4 ... Interconnection line 5 ... MMI
6 ... LFC target / exclusion switching unit 10 ... data detection unit 11 ... detection signal line 12 ... control signal line 13 ... signal lines 20-1, 20-2, ..., 20-n ... generator output Signal input units 22-1, 22-2,..., 22-n... Target command value creation units 23-1, 23-2,. ... AR decomposition part 26 ... AR distribution part 27 ... Power generation end total demand calculation part 28 ... Online prediction demand part 29 ... Previous day operation planning part 30 ... ELD schedule calculation part

Claims (6)

In the power system, a ΔF detection unit that detects a frequency change amount (ΔF), a ΔPT detection unit that detects a connection power flow change amount (ΔPT), the frequency change amount (ΔF) and the connection power flow change amount ( AR calculation unit for calculating regional required power (AR) using ΔPT), AR decomposition unit for frequency-resolving calculated regional required power (AR), and frequency-resolved regional required power (AR) for each generator An AR distribution unit to distribute, a target command value calculation unit to calculate a target command value from an ELD schedule calculated by the allocated regional demand power (AR) and economic load distribution control (ELD), and a target command to the generator In a power system load frequency control system having a command value transmission unit for transmitting a value,
On the output side of the AR distribution unit, a generator that is subject to load frequency control is switched to a target that is not load frequency controlled or a generator that is not subject to load frequency control is loaded according to the size of the regional required power (AR). A power system load frequency control system comprising a switching unit for switching to a frequency control target.   The switching unit switches a generator that is not subject to load frequency control to a generator that is subject to load frequency control when the regional required power (AR) exceeds a predetermined threshold value. The power system load frequency control system described.   The switching unit is configured to switch a load frequency control target generator when the regional required power (AR) is less than a predetermined first threshold and exceeds a second threshold smaller than the first threshold. 2. The power system load frequency control system according to claim 1, wherein the generator is switched to a generator that is not subject to load frequency control.   The switching unit performs a smoothing process on the regional required power (AR) when the number of switching times within a predetermined time exceeds a predetermined value, and the regional required power AR after the smoothing process is a predetermined value. 2. The power system load frequency control system according to claim 1, wherein a generator that is not subject to load frequency control is switched to a generator that is subject to load frequency control when the threshold value is exceeded.   The switching unit performs a smoothing process on the regional required power (AR) when the number of switching times within a predetermined time exceeds a predetermined value, and the regional required power AR after the smoothing process is a predetermined value. The generator of load frequency control is switched to a generator that is not subject to load frequency control when a second threshold that is less than the first threshold and exceeds a second threshold that is less than the first threshold. Item 4. The power system load frequency control system according to Item 1.   When there are a plurality of generators subject to load frequency control or not subject to load frequency control, the switching unit selects a generator according to the priority assigned by the operator and switches the generator. The power system load frequency control system according to any one of claims 1 to 5, wherein the system is performed.

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